The present disclosure relates to a fixing device configured to fix a toner image onto a recording medium and an image forming apparatus including the fixing device.
Conventionally, an electrographic image forming apparatus, such as a copying machine or a printer, includes a fixing device configured to fix a toner image onto a recording medium, such as a sheet.
For example, there is a fixing device including a fixing belt, a pressuring member configured to come into pressure contact with the fixing belt so as to form a fixing nip, a heat source configured to heat the fixing belt and a pressing member configured to press the fixing belt to a side of the pressuring member.
In such a fixing device, in a case where the heat source heats the fixing belt in a state that the fixing belt is not rotating, there is a risk that the temperature of the fixing belt excessively rises. Therefore, the above-mentioned fixing device is provided with a rotation detecting means configured to detect a rotation state of the fixing belt. The rotation detecting means includes a roller configured to be co-rotated with the rotation of the fixing belt, a rotation transmitting device configured to output a rotation of the fixing belt with an increased state by using a rotation of the roller as an input, and a photo sensor configured to detect the rotation state of the fixing belt based on the output of the rotation transmitting device.
In the fixing device configured as described above, the rotation detecting means requires the roller and the rotation transmitting device in addition to the photo sensor, which leads to a complicated configuration of the rotation detecting means.